Fuse construction



June 30, 1942. H. A. TRIPLETT 2,288,117

FUSE CONSTRUCTION Filed Aug. 16, 19 39 4 Sheets-Sheet l flacwfr 1221/ 7? Q45 mpzezf June 30, 1942. H. A. TRIPLETT FUSE CONSTRUCTION Filed Aug. 16, 1939 4 Sheets-$heet 2 Q ZQEHEDMZN xx Q Q g 0 \N w%. Q Q. Q

June 30, 1942- H. A. TRIPLETT FUSE CONSTRUCTION Filed Aug. 16, 1939 4 Sheets-$heet 3 June 30, 1942. TRlPLETT I 2,288,117

FUSE CONSTRUCTION Filed Aug. 16, 1939 4 Sheets-Sheet 4 Patented June 30, 1942 ururso srn'res FUSE CONSTRUCTION Hugh A. Triplett, Wilmette, Il1., assignor to Schweitzer & Conrad, Inc., Chicago, 111., a corporation of Delaware i ATENT OFFICE 37 Claims,

This invention relates, generally, to electrical circuit interrupting apparatus and it has particular relation to improvements in the construction of such apparatus for use on high tension electric power circuits such as 66,000 volt circuits.

The object of this invention, generally stated, is to provide an improved form of high tension electric circuit interrupting apparatus which shall be simple and efficient in operation and which may be readily and economically manufactured, installed and replaced.

An important object of this invention is to interrupt a high tension electric circuit promptly upon the occurrence of a fault, in such manner as to provide a maximum effective length of creepage distance over the material subjected to the action of the arc or arcs drawn on interruption of the circuit, with a minimum of space between the terminals of the interrupted circuit.

Another important object of this invention is to provide for interrupting the circuit at two series connected portions in a new and improved manner.

Still another important object of this invention is to provide for lengthening an arc at a speed that is substantially higher than the speed of the operating means causing the arc to lengthen.

A further important object of this invention is to so arrange a pair of circuit interrupters in a tubular housing that proper functioning is effected within a minimum of length of housing.

Another object of this invention is to provide for distributing dielectric stress between the terminals of high tension circuit interrupting apparatus having circuit interrupting means at each end.

A further object of this invention is to increase the leakage distance or creepage path at each end of a horizontally mounted tubular fuse housing and to provide for moisture to be carried away in spaced streams from these ends.

Still another object of this invention is to provide operating means individual to each of a pair of series connected blast action are extinguishing devices.

A further object of this invention is to provide for securing a renewable circuit interrupting device having a fixed terminal at each end in position within a housing and for electrical connection thereto.

Other objects of this invention will in part be obvious and, in part, appear hereinafter.

Accordingly, the invention is disclosed in the 5 embodiments thereof shown in the accompanydrawings, and it comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the constructions hereinafter set forth, and the scope of the application of which will be indicated in the appended claims,

For a more complete understanding of the nature and scope of this invention, reference may be had to the following detailed description, taken in connection with the accompanying drawings, in which:

Figure 1 is a view, in side elevation, of circuit interrupting apparatus constructed in accordance with this invention and mounted upon a pair of line insulators, only the upper portions of which are shown;

Figure 2 is a view in end elevation, at an enlarged scale, of the apparatus shown in Figure 1, the rain shields being omitted;

Figure 3 is a longitudinal sectional view of a housing for a circuit interrupter constructed according to this invention, the replacable circuit interrupting portion thereof being shown in elevation;

Figures 4A and 4B, taken together, show a longitudinal sectional view, at an enlarged scale, of the replaceable circuit interrupting apparatus shown in Figure 3;

Figures 5, 6 and "I are longitudinal views similar to that shown in Figur an. ,4 illustrate diiierent alternate constructi us that may be employed; and.

Figures 8A and 8B, taken together, iiius another embodiment of the invention.

Referring now particularly to Figures 1 and of the drawings, it will be observed that the ref erence character if? designates, generally, a circult interrupter which is constructed nccord ance with the present invention and wh. particularly adapted for use on high tension cir cuits, for example, circuits operating at and above 65,060 volts. The circuit interrupter it is intended for use in a circuit that is adapted to carry power current in contra-distinction to circuit interrupters that are employed in connection with metering circuits, in which case they are connected between the primary winding of a potential transformer and the circuit The circuit interrupter it is intended to carry normal load current and to quickly and efficiently interrupt the circuit in the event that a fault occurs thereon. It will be appreciated that the problems involved in such an application are considerably different from those which are met when it is only necessary to consider a metering load.

The circuit interrupter i6 is provided with ex" ternal terminals shown, generally, at H and i2 and they are arranged to be connected to circuit terminals I3 and. 14 by suitable readily operable clamp mechanisms, shown, generally, at i5 and I6. The details of construction of the clamp mechanisms I5 and It are set forth in Patent No. 2,147,316, issued February 14, 1939, to Allan Ramsey and assigned to the assignee of this application. Since the clamp mechanisms I5 and I6 form no part of the present invention, further description thereof herein will be omitted.

The circuit terminals I3 and I4 have connected thereto the usual line conductors and, as indicated, they may be energized at a potential of 66,000 volts. The circuit terminals I3 and I4 are suitably mounted on insulators I1 and I3, only the upper portions being illustrated, and are secured thereon by suitable clamp mechanisms I9 and 20.

Rain shields 2I and 22 are provided at the ends of the circuit interrupter IE! for preventing the entrance of moisture after it has operated leaving the ends, which are normally closed, open.

After the circuit interrupter I has operated, the clamp mechanisms I and I6 are operated as described in said Patent No. 2,147,316, to Ramsey, by a suitable switch stick, and the circuit interruptor I0 is then removed. After the circuit interrupter III has been re-fused, it is inserted in position on the circuit terminals I3 and I4 and clamped in position by the clamp mecha nisrns I5 and I6, as will be readily understood.

Referring now particularly to Figures 3 and 4A and 4B, it will be observed that the circuit interrupter I0 comprises a generally tubular housing 23, formed preferably of glass or porc lain, within which there is provided a generally cylindrical replaceable circuit interrupting device designated generally at 24. The details of construction of the replaceable circuit interrupting device 24 are shown more clearly in Figures 4A and 43.

At each end of the replaceable circuit interrupting device 24 there is provided a circuit interrupting unit 25 and 26, as illustrated. At the extreme ends of the replaceable circuit interrupting device 24 there are provided fixed terminals 21 and 28, each individual to the circuit interrupting units 25 and 26, respectively.

As shown in Figure 3 of the drawings, the replaceable circuit interrupting device 24 is arranged to be positioned within the housing 23. The construction is such that the replaceable circuit interrupting device 24 is inserted from the left-hand end of the housing 23 a viewed in Figure 3. In the operating position, the fixed terminals 21 and 28 register with the external terminals H and I2 and are electrically connected thereto in order to complete the electrical circuit through the circuit interrupter Iii, and are 7 whereby the movement of the replaceable circuit interrupting device 24 is limited to locate it in the desired position within the housing 23, with the fixed terminals 21 and 28 in registry with the external terminals II and I2, as will be readily understood. A clamp nut 35, threaded on the left-hand end of the ferrule 3i, serves not only to insure electrical contact engagement between the ferrule 3I and the fixed terminal 21, but also, because of the overhanging flange 36, the fixed terminal 2? and thereby the replaceable circuit interrupting device 24 is held against longitudinal movement relative to the housing 23. It will be observed that the fixed terminal 35 is provided with a central opening 31 through which the products of the are formed on operation of the circuit interrupting unit 25 may be readily discharged, as will be described in more detail hereinafter.

The ferrule 3I is provided with an outwardly extending flange 38 for definitely locating the left-hand end of the housing 23 with respect to the clamp mechanism [5, Figure l.

The external terminal I2 at the right-hand end of the housing 23 is provided with a ferrule 49 which may be secured to the end of the housing 23 b any suitable means, such as by alloy M, as illustrated. Within the ferrule 46 there is provided a clamp ring 42 that is split, as indicated at 43. The clamp ring 42 is arranged to encircle the fixed terminal 28 at the right-hand end of the replaceable circuit interrupting device 24. The clamp ring 42 is held in place by means of a pin 44 that extends through an external flange 45 of the ferrule 40. It will be understood that the flange 45 serves to definitely position the right-hand end of the housing 23 in the clamp mechanism I6, Figure 1. In order to tighten the clamp ring 42 against the fixed terminal 28, a thumb screw 46 is provided on the side of the ferrule 40 opposite to the section thereof as shown in Figure 3 of the drawings. When the thumb screw 46 is tightened, the split clamp ring 42 grips the fixed terminal 28 and not only provides electrical connection between the ferrule 46 and the fixed terminal 28, but also it clamps the right-hand end of the replaceable circuit interrupting device 24 so that it cannot move longitudinally with respect to the housing 23. The inner surface of the split clamp ring 42 is chamfered slightly, as indicated at 41, in order to facilitate entry of the fixed terminal 28. As shown, the ferrule 40 is open at 48 in order to provide for free flow of the products of the are from the circuit interrupting unit 26, as will be described in detail hereinafter.

After the circuit interrupting units 25 and 26 have operated, it will be appreciated that a difference of potential equal to the line voltage will exist between the external terminals II and I2 following the operation of one device in a single or three phase installation. As a result, a very high dielectric stress occurs in the housing 23. With a view to uniformly distributing this dielectric stress, so that it will not be concentrated at points adjacent the ends of the housing 23, a number of corrugations or outwardly extending ridges, 49 and 50, are integrally formed with the housing 23.

Since the housing 23 is mounted in a horizontal position the leakage current flowing over it following fuse operation during a driving rain might be suflicient to result in destruction of the housing 23 if the corrugations 49 and 50 were not provided. Obviously the corrugations 49 and 50 increase the leakage distance or creepage path over the exterior of the housing 23 between the external terminals II and I2 which might be contaminated with dirt following installation. The corrugations 49 and 59 on the horizontally mounted housing 23 are particularly effective for the reason that a driving rain will thoroughly clean them and the streams of water running off of them will be spaced apart and not come together as is the case when corrugations are provided on a vertically mounted housing.

The details of construction of the replaceable circuit interrupting device 24 are more clearly shown in Figures 4A and 4B, as previously indicated. It will be recalled that this device, as a unit, is intended to be inserted into the housing 23 and clamped therein. Two series circuit interrupting units 25 and 25 are provided, one at each end of the refill unit assembly, and each is arranged to assist in the interruption of the circuit so that two open portions of the circuit are provided between the circuit terminals I3 and I4, Figure 1. It is, of course, desirable to have the length of the housing 23 at a minimum and yet it is essential that suitable clearances be provided and sufficient creepage distances be employed as will prevent restriking of the are or arcs after the circuit has once been opened. It will thus be evident that the operating mechanism must be compact and capable of performing its intended function within these space requirements,

The circuit interrupters 25 and 25 at the ends of the replaceable circuit interrupting device 24 are provided with insulating housings 55 and 55 formed of suitable insulating material such as a phenolic condensation product. Within the housings 55 and 55 there is provided a mass of solid arc extinguishing material, such as boric acid, in the form of sections 51 and 58, respectively, through which centrally located bores 59 and 86 extend. An arc is formed between each movable terminal GI and 62 and its adjacent fixed terminal 21 and 28, respectively, the arcs thus formed being drawn into the bores 59 and 55, as will presently be described, and extin- I 53 and a l, preferabl formed of silver wire, and t strain elements 65 and 66, preferably formed of high strength material, to metallic sleeves 61 and 58 which are secured by any suitable means, such as screws 69 and III, to the fixed terminals 21' and 28. The terminals GI and 62 are preferably in the form of metallic sleeves and they and the sleeves 61 and 68 are deformed onto the ends of the fusible elements 63 and 54 and the strain elements 65 and 66, in order to mechanically secure them thereto and to provide electrical connection therewith.

The end sections 51 and 58 have the bores 59 and 69 therein flared outwardly, as indicated at H and I2, in order to facilitate the expulsion of the products of the arcs formed thereat. The flared-out portions II and I2 form part of arcing chambers which are continued into end rings 73 and 14, preferably formed of fiber. In order to prevent the entrance of extraneous material into the arcing chambers, the openings I5 and 1'5 in the fixed terminals 21 and 28 are closed by closure members TI and I8, preferably in the form of mica discs.

Retainer sleeves 8| and 82, formed of metal, are provided at the inner ends of the housings and 56 and, as illustrated, have threaded connection therewith. Washers 83 and 84, preferably formed of fiber, are provided between the retainer sleeves 8| and 82 and the adjacent sections 5'! and 58 of the solid arc extinguishing material in order to accommodate slight variations in the sizes of the sections 5? and 58, it being understood that different thicknesses of the washers 83 and 84 may be employed.

With a view to holding the circuit interrupting units 25 and 25 in end-to-end relation, a sleeve 85 in the form of a metallic tube is provided therebetween and is threaded, as shown, onto the retainer sleeves 8i and 82. The sleeve 85 serves as a strut between the circuit interrupting units 25 and 26 and, since it is formed of conducting material, it serves to electrically interconnect them.

Now it is desirable to withdraw the terminals 6i and 62 within their respective bores 59 and at a relatively high speed. It is also desirable to provide a relatively long length of bore in each case because of the voltage of the circuit involved, in order that a sufficient creepage distance will be provided over the surface of the bores 59 and Gil after the circuit has been opened, as will render unlikely the leakage of current thereacross, with its attendant disadvantages. Despite the long length of travel of the terminals 6| and 62 that is necessary, it is at the same time desirable that an operating mechanism be employed which requires as little space as possible for its movement to the open circuit position.

With these requirements in mind, operating means is provided which effect movement of the terminals 5i and 52 through a much greater extent of movement than is required by the operating means to effect this movement. Flexible leads 8'! and 88 are connected to the terminals 6| and 62, the latter being deformed onto the ends of the former, and they are then looped over pulleys I35 and 99 that are rotatably mounted on shafts SI and 92 carried by pulley blocks 93 and 94. The pulley blocks '53 and 95 are generally cylindrical in shape, and are relatively slidable within the sleeve 85. The pulley blocks 93 and 95 are provided with cup-shaped portions 95 and 95 for receiving coil compression springs 97 and 98. As shown, the springs 9? and 98 react against shoulders 99 and I55 of the retainer sleeves BI and 82. The ends of the flexible leads 5! and 88 that are looped over the pulleys 89 and 90 are provided with terminal sleeves I5! and I92 that may be secured by suitable means, such as screws I93 and I94 to the recessed portions I05 and I55 of the retainer sleeves 8! and 82.

The electrical circuit through the replaceable circuit interrupting device 24, prior to operation of the circuit interrupting units 25 and 25, will now be apparent. It may be traced as follows: From the fixed terminal 27 at the left-hand end through the sleeve 51, fusible and strain elements 63 and 65, in parallel, terminal 5|, flexible lead 81, terminal sleeve I 5|, retainer sleeve 8!, corn necting sleeve between the circuit interrupting units 25 and 26, retainer sleeve 82, terminal sleeve I92, flexible lead 88, terminal 52, fusible and strain elements 64 and 65, in parallel, terminal sleeve 58, to the fixed terminal 23 at the right-hand end of the replaceable circuit interrupting device 25. Since the fixed terminals 27 and 28 are clamped to the external terminals II and I2, respectively, which are in turn connected to the circuit terminals I3 and I4, respectively, the complete circuit between these circuit terminals I3 and I4 will be apparent.

Since the flexible leads 8'! and 8B are looped over the pulleys 89 and 90, any longitudinal movement thereof through the sleeve 85 toward each other under the influence of the compression springs 9'! and 98 will cause a. movement of the terminals 6! and 62 individual thereto through twice the extent of longitudinal movement of the pulleys 89 and 90 and their pulley blocks 93 and 94. By thus multiplying the movement of the pulley blocks 93 and 94 in the movement of the terminals 6| and 62, it is possible to employ a shorter length of sleeve 85 than would otherwise be the case if such a multiplying action were not present.

The movement of the pulley blocks 93 and 94 is limited by means of a stop pin III! that is positioned transversely to the sleeve 85 substantially midway of its ends.

In operation, on the occurrence of a fault on the circuit to which the circuit terminals I3 and I4 (Figure l) are connected, fusible elements 63 and 64 are melted, together with the strain elements 65 and 66. For all practical purposes, this will occur substantially simultaneously so that substantially at the same time the movable terminals 6| and 62 are released for movement through their respective bores 59 and 60 under the influence of the coiled compression springs 9'! and 98 which promptly extend and drive the pulley blocks 93 and 94 toward the stop pin I91. Since the ends of the flexible leads 8'! and 88 to which the terminal sleeves I! and I02 are connected are stationary, for each unit of movement of the pulley block 93 and 94, twice such movement of the movable terminals BI and 62 through'the bores 59 and 60 takes place. Because of the heat of the arcs drawn between the terminals BI and 62 and their corresponding fixed terminals 2'! and 28, an arc extinguishing medium is evolved from the surface of the bores 59 and 60 which, as described, serves to assist in extingushing these arcs. Because two arcs are drawn in series, it is much easier to extinguish them than is the case if a single arc were drawn within a bore of solid arc extinguishing material that is twice as long as one of the bores 59 or 69. Thus, because two arcs are drawn in series, and each bore 59 and 60 may be substantially twice the length of the space required for the movement of the pulley blocks 93 and 94, it is possible to satisfactorily interrupt a high voltage circuit and at the same time provide the necessary dielectric strength following short circuit operation.

After the circuit has been opened as described, the circuit interrupter III, Figure l, is bodily removed. The replaceable circuit interrupting device 24, Figure 3, is then unclamped and removed and a new one is substituted for it or it is refused. The circuit interrupter ID is then placed in operative position on the circuit terminals I3 and M, Figure 1.

In Figure of the drawings the left-hand end of a replaceable circuit interrupting device, shown generally at H2, is illustrated. This construction is generally similar to that construction shown in Figure 4A, described hereinbefore. differs in the following respects. A rod-like terminal H3 is provided within the bore 59 of the sections 5'! of solid arc extinguishing material. The fusible and strain elements 93 and '55 are secured to one end by its being deformed thereon. One end of a flexible lead 8'! is se cured by having the other end of the rod-like terminal H3 deformed thereon, as indicated at H4. The retainer sleeve H5 is somewhat dififerent in construction from the retainer sleeve 8I. It is adapted to receive an insulating member H6 having a flanged portion II'! corresponding to the washer 83 and a tubular neck portion I I9 through which the flexible lead 8'! and the rodlike terminal H3 are withdrawn.

In Figure 6 of the drawings, a replaceable circuit interrupting device is shown generally at I2I, which is constructed somewhat along the lines of the replaceable circuit interrupting device 24 shown in Figure 4A and 4B. However, it differs in certain respects, the principal difference being that an operating means common to both of the circuit interrupting units is provided for operating them. In the construction shown in Figure 6, a tubular housing I22 extends from one end of the device I2! to the other. At the left-hand end a fixed terminal 2'! is provided which is similar to the terminal 2'! previously described. At the right-hand end, a terminal (not shown) is provided that is similar to the terminal 28 previously described. At each end of the tubular housing I22 there is provided the sections 5'! and 59 of solidarc extinguishing material having the bores 59 and centrally located therein.

Within the bore 59 there is provided a rodlike terminal I23 extending throughout substantially its entire length. At its left-hand end there are secured fusible and strain elements 63' and respectively. In this construction only the fusible element 63 is secured to the terminal sleeve 61, while the strain element 65 is looped over a pin I 24 that extends transversely of the fixed terminal 27'. By providing this construction it is possible to more directly restrain the tendency of the rod-like terminal I23 to move through its bore 59.

At the right-hand end there is provided a rodlike terminal I26 which is similar to the terminal I23. The inner ends of the rod-like terminals I23 and I26 are provided with enlarged portions I2! and I28 about which the end convolutions of a coiled tension spring I29 are wound, the extreme ends being suitably secured thereto as by being inserted in suitable apertures therein. Tubular terminal portions I3I and I32 are integrally formed with the rod-like terminals I23 and IE5 and are deformed onto the ends of a flexible lead I33 which extends substantially coaxially of the spring I29. A pin I34 extending transversely of a sleeve I35 and located midway its ends, serves to control the position of the spring I29 after it has retracted. The sleeve I35 extends between the sections 5'! and 58 of solid are extinguishing material and may be formed of metal, as shown, or, if desired, of insulation. In this case its sole function is to serve as a strut or spacer between the sections of are extinguishing material. It will be evident that, if movement of the rod terminal I23 in Figure 6 is made equivalent to the terminal movement in Figures 4A, 4B, and 5, the spacing between the circuit interrupting elements will have to be approximately twice that allowed in these other designs.

In Figure '7 of the drawings, one end of the replaceable circuit interrupting unit, shown generally at I49, is illustrated, which comprises certain features shown in Figures 4A and 6, in addition to certain other features.

A terminal MI is provided for movement in the bore 59 of the sections 51 of solid are extinguishing material, this terminal being of somewhat different construction than the terminal 6i, Figure 4A, and is shorter than the rodlike terminal II 3, Figure 5. One end of the terminal MI is deformed onto the fusible and strain element 63 and 65, as illustrated, while its other end is deformed onto a flexible lead 81 that is looped over the pulley 86. The flexible lead 81 extends through a retainer sleeve I42 and guided in its movement therethrough by means of transverse pins I43, the pins M2 being spaced sufficiently far apart so that the flexible lead 81 moves freely therebetween, but spaced near enough together so that the terminal I4I cannot pass therebetween. The end of the flexible lead 81 and the terminal I4I attached thereto then cannot be snapped toward the other end of the device after the pulley block 93 has come to rest against the stop pin I01.

The end of the flexible lead 81 that is looped over the pulley 88 is secured to a terminal I44, one end I45 of which is deformed thereon while the other end 546 is threaded into a suitable tapped aperture in the retainer sleeve I42.

Another embodiment of the invention is shown in Figures 8A and 8B which show, respectively, the ends of a circuit interrupter, illustrated generally at I50, the distance between the ends depending upon the necessary length of the operating mechanism, and the interrupter being adapted to be employed in lieu of the circuit interrupter I of Figure 1. The circuit interrupter I50 embodies many of the features of the embodiments described hereinbefore and it differs therefrom particularly with regard to the arrangement of the operating mechanism for withdrawing the movable terminal of each circuit interrupting unit, together with the necessary modifications which go to make up the alternate construction.

The circuit interrupter I50 may be provided with a housing 23' which is generally similar to the housing 23, Figure 3. At its ends, corrugations or ridges 40 and 55 are provided for distributing the dielectric stress which exists after the circuit has been interrupted and for increasing the leakage distance as described.

At each end of the housing 23' an external terminal, shown generally at I SI and I52, is provided.

The external terminal I5I is arranged to receive the circuit interrupting units therethrough, while the terminal I 52 is merely arranged for mechanical and electrical connection to the corresponding fixed terminal of the circuit interrupting unit thereat. It will be observed that the external terminal i5i comprises a ferrule 553 which may be secured by any suitable means, such as alloy I54, to the end of the housing 23. The ferrule I53 is internall threaded for receiving a spanner nut 55, the function of which will be presently set forth.

Within the housing 23 two circuit interrupting units, generally designated as I51 and I58, are provided. These circuit interrupting units are generally identical in construction except for the arrangement of the fixed terminal on the unit I58 to permit it being inserted through the ferrule I53 of the external terminal I5I. Accordingly, the

description of one will sufiice for that of the other.

The circuit interrupting unit I51 is provided with a tubular housing I59 that may be formed of suitable insulation, such as a phenolic condensation product. Within the housing I59 there is provided a filling of solid arc extinguishing material, such as boric acid, and for convenience it is formed in the sections I69 thereof. A longitudinal bore I6I extends through the sections I60 of solid arc extinguishing material. For reasons which will presently be described, the bore I6l is ofiset from the center of the sections I60. Movably mounted within the bore I6I is a rod-like terminal I62, the left-hand end of which is deformed onto fusible and strain elements I63 and I64. These elements are secured by means of a terminal sleeve 555 which is fastened by a screw I66 to a fixed terminal I61 threaded on the left-hand end of the housing l59. The fusible and strain elements I63 and le t are positioned in an arcing chamber in a sleeve I68 of insulation, preferably fiber. As shown, this arcing chamber is flared outwardly to factilitate the expulsion of the products of the are formed therein.

The right-hand end of the housing I59 is pro vided with a retainer sleeve I69 of metal which reacts against a washer I 10, preferably formed of fiber, and serves to hold the sections I60 of solid arc extinguishing material in place. As shown, the rodlike terminal E62 extends through the retainer sleeve I69 into a tubular sleeve I1I which is threaded into a suitable internally threaded boss of the retainer sleeve I69. The sleeve I1I may be formed of metal or insulation, as may be desired. The showing in the drawings is metal.

The sleeve I1I forming a part of the circuit interrupting unit I51 extends toward the other circuit interrupting unit I58 and alongside of its corresponding tube. In order to permit the insertion of the circuit interrupting units I51 and I58 as shown, it is necessary that the bore I61 in the sections I60 of solid arc extinguishing material be oiiset so that these tubes may be placed alongside of each other.

The rodlike terminal I62 is provided with an enlarged end portion I12 around which the end convolutions of a coiled tension spring I13 are placed, the end of the spring I13 being secured thereto by being turned into a suitable aperture therein. The other end of the spring I13 is secured at the other end of the tube "I. Since the construction of the circuit interrupting units I 51 and I58 is identical in this respect, reference may be had to the attachment of the spring I13 of the circuit interrupting unit I58. As shown, the end convolutions of the spring I13 are turned about a boss I14, with the extreme end portion being secured thereto by being turned inwardly into a suitable aperture therein. The boss I14 forms an integral part of a fitting I15 which is threaded into the end of the sleeve I1I', as shown. The fitting I15, which is formed of metal, bears against the retainer sleeve I69 and provides for electrical contact engagement therewith.

The rod-like terminal I62 is connected with the remote end of the tube I1I by means of a flexible lead I16, one end of which is secured by deforming thereon a terminal portion I11 which constitutes an extension of the enlarged portion I12 of the rod-like terminal I62. The other end of the flexible lead I16 is secured in place in a manner similar to that in which the flexible lead I11 of the circuit interrupting unit I58 is secured. As shown, this flexible lead is secured in osition by having a terminal portion I18 of the boss I14 deformed thereon.

When the circuit interrupter I51 is placed in operative position, the right-hand end of the fixed terminal I61 abuts against an inwardly extending flange IBI of the ferrule I53. The spanner nut I55 serves to hold the fixed terminal I61 in this position and thereby the circuit interrupter I51, as well as the circuit interrupter I58, is held in position within the housing 23 against longitudinal movement therewith.

In operation, upon occurrence of a fault on the circuit'in which the circuit interrupter I50 is connected, the fusible and strain elements I63 and I54 of both of the circuit interrupting units I51 and I58 are blown substantially simultaneously. The springs I13 and I13 then retract their respective rod-like terminals to extend the arcs withinthe bores in the bodies of solid arc extinguishing material. As before, two arcs are formed in series circuit relation and, because of this fact, are more readily extinguished. Also as before, an arc extinguishing medium is evolved from the solid arc extinguishing material to assist in extinguishing the arcs thus formed. After the circuit has been interrupted, the circuit in terrupter I50 is bodily removed from its normal position. The spanner nut I55 is then removed, the clamp means (not shown) of the external terminal I52 is released, and both of the circuit interrupting units I51 and I58 are removed from glass tube housing. The spring actuating mechanisms are disconnected from the blown circuit interrupting elements and are re-connected to unblown assemblies and replaced in the housing 23. First, the circuit interrupting unit I58 is placed in position and clamped in place in the external terminal I52. Next, the circuit interrupting unit I51 is inserted, with its sleeve I1I containing the tension spring I13 alongside of the corresponding sleeve I1I containing the spring I13 of the circuit interrupting unit I58. Care is taken so that the metallic fittings I15 and I15 at the ends of the sleeve HI and HI, respectively, are in good contact engagement with their respective metallic retainer sleeves I69 and I69. The spanner nut I55 is then tightened into position, and the circuit interrupter I50 is then ready for installation in operative position in the circuit.

What is claimed as new is:

l. A circuit interrupter for connection in a high tension electric circuit comprising, in combination, a tubular insulating housing, circuit interrupting means within said housing at each end thereof, conducting means electrically interconnecting said circuit interrupting means, and operating means within said housing disposed to function in response to the occurrence of a fault on the circuit for opening the same at each end of said housing by operation of the circuit interrupting means thereat.

2. A circuit interrupter for connection in a high tension electric circuit comprising, in combination, a tubular insulating housing, an external terminal at each end of said housing for connection to a circuit terminal, a circuit interrupting unit within said housing at each end and connected to the external terminal thereat, conducting means within said housing electrically interconnecting said units, and operating means within said housing disposed to function in response to the occurrence of a fault on the circuit for opening the same at each end of said housing by operation of the circuit interrupting unit thereat.

3. A circuit interrupter for connection in a high tension electric circuit comprising, in combination, a tubular insulating housing, an external terminal at each end of said housing for connection to a circuitterminal, a blast action circuit interrupting unit within said housing at each end adapted to discharge out of the same and connected to the external terminal thereat, conducting means within said housing electrically interconnecting said units, and operating means within said housing between said circuit interrupting units for operating the same on the occurrence of a fault on the circuit.

4. Means for interrupting a high tension electric circuit comprising, in combination, a pair of circuit terminals in insulated spaced relation, a circuit interrupter individual to each circuit terminal and connected thereto, conducting means connecting said circuit interrupters in series circuit relation, and operating means individual to each circuit interrupter for effecting operation of the same to open the circuit at two points on the occurrence of a fault on the circuit.

5. Means for interruptin a high tension electric circuit comprising, in combination, a pair of spaced insulators, a circuit terminal carried by each insulator, a generally tubular circuit interrupter connected to each circuit terminal and extending toward the other circuit terminal, conducting means interconnecting said circuit interrupters, and operating means disposed between said circuit interrupters for operating them to provide two breaks in the circuit in response to the occurrence of a fault on the circuit.

6. A circuit interrupter comprising, in combination, means for drawing an arc comprising a pair of relatively infusible terminals capable of being relatively moved apart, means stationarily mounting one of said terminals, means guiding the other terminal along a predetermined path in it movement relative to said one terminal whereby the arc therebetween is drawn in a predetermined space, movable means connected to said are drawing means in such manner that the arc is lengthened at a speed substantially in excess of the speed of movement of said movable means, and operating means for said movable means.

7. A circuit interrupter comprising, in combination, a pair of relatively movable apart terminals between which an arc is adapted to be drawn, means stationarily mounting one of said terminals, means guiding the other terminal along a predetermined path in its movement relative to said one terminal whereby the arc therebetween is drawn in a predetermined space, a movable member, means operatively interconnecting one of said terminals and said movable member in such manner that a given movement of the latter results in a substantially greater movement of the former, and means biasing said movable member for effecting such movement.

8. A circuit interrupter comprising, in combination, a pair of relatively movable apart terminals between which an arc is adapted to be drawn, means stationarily mounting one of said terminals, means guiding the other terminal bination, a pair of relatively movable apart terminals between which an arc is adapted to be drawn, means stationarily mounting one of said terminals, means guiding the other terminal along a predetermined path in its movement relative to said one terminal whereby the are therebetween is drawn in a predetermined space, a movable member, a pulley mounted on said movable member, a flexible lead secured at one end to one of said terminals and looped over said pulley, means fastening the other end of said flexible lead between said one terminal and said movable member whereby for a given movement of the latter the former moves twice as far, and spring means biasing said movable member for efiecting such movement on release of said one terminal.

10. A circuit interrupter comprising, in combination, a pair of relatively movable apart terminals, fusible means inter-connecting said terminals, means stationarily mounting one of said terminals, means guiding the other terminal along a predetermined path in its movement relative to said one terminal whereby the arc therebetween is drawn in a predetermined space, a movable pulley block, a pulley carried by said pulley block, a flexible lead secured at one end to one of said terminals and passing over said pulley, means fastening the other end of said flexible lead between said one terminal and said pulley block whereby for a, given movement of the latter the former moves twice as far, and coil spring means biasing said pulley block to effect such movement on blowing of said fusible means.

11. A circuit interrupter comprising, in combination, means for drawing an arc, a body of solid arc extinguishing material adapted to evolve an arc extinguishing medium due to the heat of the arc to assist in extinguishing and to prevent restriking of the same, movable means connected to said are drawing means in such manner that for a given movement of the former a substantially greater movement of the latter is effected, and operating means for said movable I means.

12. A circuit interrupter comprising, in combination, a body of solid arc extinguishing material having a bore from the surface of which an arc extinguishing medium is evolved due to the heat of an are, a pair of relatively movable apart terminals between which an arc is adapted to be drawn in said bore, a, member movable away from said body of solid arc extinguishing material, means extending through said bore and operatively interconnecting one of said terminals and said movable member in such manner that a given movement of the latter effects a substantially greater movement of the former, and means biasing said movable member to cause such movement.

23. A circuit interrupter comprising, in com bination, a body of solid arc extinguishing material having a bore from the surface of which an arc extinguishing medium is evolved due to the heat of an are, a pair of relatively movable apart terminals between which an arc is adapted to be drawn in said bore, a member movable away from said body of solid arc extinguishing material, a flexible lead secured at one end to one of said terminals and extending through said bore and looped over said movable member, means holding the other end of said flexible lead in such position that a given movement of said movable member causes a substantially greater movement of said one terminal through said bore, and spring means biasing said movable member away from said body of solid arc extinguishing material.

14. A circuit interrupter comprising, in com bination, a body of solid arc extinguishing material having a bore from the surface of which an arc extinguishing medium is evolved due to the heat of an are, a pair of relatively movable apart terminals between which an arc is adapted to be drawn in said bore, a member movable away from said body of solid arc extinguishing material, a pulley mounted on said movable member, a flexible lead secured at one end to one of terminals and extending through said bore and looped over said pulley, means fastening the other end of said flexible lead between said body of solid arc extinguishing material and said movable member whereby for a given movement of the latter said one terminal moves twice as far, and spring means biasing said movable member for efiecting such movement on release of said one terminal.

15. A circuit interrupter comprising, in combination, a body of solid arc extinguishing material having a bore from whose surface an arc extinguishing medium is evolved due to the heat of an arc, a pair of terminals relatively movable apart in said bore, fusible means interconnecting said terminals, a pulley block movable away from said body of solid arc extinguishing material, a pulley carried by said pulley block, a flexible lead secured at one end to one of said terminals and extending through said bore and passing over said pulley, means fastening the other end of said flexible lead between said body of solid arc extinguishing material and said pulley block whereby for a given movement of the latter said one terminal moves twice as far, and a coil compression spring interposed between said body of solid arc extinguishing material and said pulley block for effecting such movement on blowing of said fusible means.

16. A circuit interrupter for use on high tension circuits comprising, in combination, a tubular insulating housing; a circuit interrupter within said housing at each end each including, means for drawing an arc, means movable towards the other circuit interrupter and connected to said are drawing means in such manner that the arc is lengthened at a speed substantially in excess of the speed of movement of said movable means, and operating means for said movable means; and interrupting means electrically interconnecting said circuit interrupters.

17. A circuit interrupter for connection in a high tension electric circuit comprising, in combination, a tubular insulating housing, an exte nal terminal at each end of said housing for connection to a circuit terminal; a circuit interrupting unit Within said housing at each end each including, a pair of relatively movable apart terminals between which an arc is adapted to be drawn and one of which is connected to the external terminal thereat, a member movable towards the other circuit interrupting unit, means operatively interconnecting the other of said terminals and said movable member in such manner that a given movement of the latter results in a substantially greater movement of the former, and means biasing said movable member for effecting such movement; and conducting means within said housing electrically interconnecting said circuit interrupting units.

18. A circuit interrupter for connection in a high tension electric circuit comprising, in combination, a tubular insulating housing, an external terminal at each end of said housing for connection to a circuit terminal; a circuit interrupting unit within said housing at each end each including, a pair of relatively movable apart terminals between which an arc is adapted to be drawn and one of which is connected to the external terminal thereat, a member movable towards the other circuit interrupting unit, a flexible lead secured at one end to the other of said terminals and looped over said movable member, means holding the other end of said flexible lead in such position that a given movement of said movable member causes a substantially greater movement of said other terminal, and spring means biasing said movable member for effecting such movement; and conducting means within said housing electrically interconnecting the flexible leads of said circuit interrupting units.

19. A circuit interrupter for connection in a high tension electric circuit comprising, in combination, a tubular insulating housing, an external terminal at each end of said housing for connection to a circuit terminal; a circuit interrupting unit within said housing at each end each including, a pair of relatively movable apart terminals between which an arc is adapted to be drawn and one of which is connected to the external terminal thereat, a member movable towards the other circuit interrupting unit, a pulley mounted on said movable member, a flexible lead secured at one end to the other of said terminals and looped over said pulley, means fastening the other end of said flexible lead between said other terminal and said movable member whereby for a given movement of the latter the former moves twice as far, and spring means biasing said movable member for effecting such movement on release of said one terminal; and conducting means within said housing electrically interconnecting the flexible leads of said circuit interrupting units.

20. A circuit interrupter for connection in a high tension electric circuit comprising, in combination, a tubular insulating housing, an external terminal at each end of said housing for connection to a circuit terminal; a circuit interrupting unit within said housing at each end each including, a pair of relatively movable apart terminals one of which is connected to the external terminal thereat, fusible means interconnecting said terminals, a pulley block movable towards the other circuit interrupting unit, a pulley carried by said pulley block, a flexible lead secured at one end to the other of said terminals and passing over said pulley, means fastening the other end of said flexible lead between said other terminal and said pulley block whereby for a given movement of the latter the former moves twice as far, and coil compression spring means biasing said pulley block towards the other circuit interrupting unit to effect such movement on blowing of said fusible means; and conducting means within said housing electrically interconnecting the flexible leads of said circuit 1 interrupting units.

21.- A circuit interrupter for use on high tension circuits comprising, in combination, a tubular insulating housing; a circuit interrupter within said housing at each end each including, means for drawing an arc, a body of solid arc extinguishing material adapted to evolve an arc extinguishing medium due to the heat of the arc to assist in extinguishing and to prevent restriking of the same, movable means connected to said are drawing means in such manner that for a given movement of the former a substantially greater movement of the latter is effected, and operating means for said movable means; and conducting means electrically interconnecting said are drawing means.

22. A circuit interrupter for connection in a high tension electric circuit comprising, in combination, a tubular insulating housing, an ex ternal terminal at each end of said housing for connection to a circuit terminal; a circuit interrupting unit within said housing at each end and connected to the external terminal thereat each including, a body of solid arc extinguishing material having a bore from the surface of which an arc extinguishing medium is evolved due to the heat of an arc, a pair of relatively movable apart terminals between which an arc is adapted to be drawn in said bore and one of which is connected to the external terminal thereat, a member movable away from said body of solid arc extinguishing material towards the other circuit interrupting unit, means extending through said bore and operatively interconnecting the other of said terminals and said movable member in such manner that a given movement of the latter effects a substantially greater movement of the former, and means biasing said movable member to cause such movement; and conducting means within said housing electrically interconnecting the other terminals of said circuit interrupting units.

23. A circuit interrupter for connection in a high tension electric circuit comprising, in combination, a tubular insulating housing, an external terminal at each end of said housing for connection to a circuit terminal; a circuit interrupting unit within said housing at each end and connected to the external terminal thereat each including, a body of solid arc extinguishing material having a bore from the surface of which an arc extinguishing medium is evolved due to the heat of an arc, a pair of relatively movable apart terminals between which an arc is adapted to be drawn in said bore and one of which is connected to the external terminal thereat, a member movable away from said body of solid arc extinguishing material towards the other circuit interrupting unit, a flexible lead secured at one end to the other of said terminals and extending through said bore and looped over said movable member means holding the other end of said flexible lead in such position that a given movement of said movable member causes a substantially greater movement of said other terminal through said bore, and spring means biasing said movable member away from said body of solid are extinguishing material; and conducting means within said housing electrically interconnecting the flexible leads of said circuit interrupting units.

24. A circuit interrupter for connection in a high tension electric circuit comprising, in combination, a tubular insulating housing, an external terminal at each end of said housing for connection to a circuit terminal; a circuit interrupting unit within said housing at each end and connected to the external terminal thereat each including, a body of solid arc extinguishing material having a bore from the surface of which an arc extinguishing medium is evolved due to the heat of an arc, a pair of relatively movable apart terminals between which an arc is adapted to be drawn in said bore and one of which is connected to the external terminal thereat, a member movable away from said body of solid arc extinguishing material towards the other circuit interrupting unit, a pulley mounted on said movable member, a flexible lead secured at one end to the other of said terminals and extending through said bore and looped over said pulley, means fastening the other end of said flexible lead between said body of solid arc extinguishing material and said movable member whereby for a given movement of the latter said other terminal moves twice as far, and spring means biasing said movable member for efiecting such movement on release of said one terminal; and conducting means within said housing electrically interconnecting the flexible leads of said circuit interrupting units.

25. A circuit interrupter for connection in a high tension electric circuit comprising, in combination, a tubular insulating housing, an external terminal at each end of said housing for connection to a circuit terminal; a circuit interrupt ing unit within said housing at each end and connected to the external terminal thereat each in cluding, a body of solid arc extinguishing material having a bore from the surface of which an arc extinguishing medium is evolved due to the heat of an arc, a pair of relatively movable apart terminals between which an arc is adapted to be drawn in bore and one of which is connected to the external terminal thereat, fusible means interconnecting said terminals, a pulley block movable away from said body of solid arc extinguishing material, a pulley carried by said pulley block, a flexible lead secured at one end to the other of said terminals and extending through said bore and passing over said pulley, means fastening the other end of said flexible lead between said body of solid arc extinguishing material and said pulley block whereby for a given movement of the latter said other terminal moves tw as far, and a coil compression spring interposed between said body of solid are extinguishing material and said pulley block for effecting such movement on blowing of said fusible means; conducting means within said housing electrically interconnecting the flexible leads of said circuit interrupting units.

26. A c' 'cuit interrupter for use on high tenelectric circuits comprising, in combination, a tubular insulating housing, circuit interrupting means within said housing at each end thereof, operating means within said housing and common to both said circuit in errupting means, and conducting means electrically interconnecting said circuit interrupting means.

27. for interrupting a high tension electric circuit comprising, in combination, a pair of circuit te inals in insulated spaced relation, a ter individual to each circuit terminal and c nested thereto, operating means coma on to d circuit interrupters and arranged ard. adapted to automatically efiect operation ti ,-eof on the occurrence of a fault in the circuit, conducting means electrically interconnecting said circuit interrupters in series circuit relation.

28. A circuit interrupter comprising, in combination. a body of solid arc extinguishing material having ore from the surface of which an arc extingui ng medium is evolved due to the heat of an arc, a pair of relatively movable apart terminals between which an arc is adapted to be drawn in said bore, a flexible lead connected to one of said terminals and extending out of said bore,

means for drawing said flexible lead through said bore on operation of the interrupter, and means for limiting the movement of said flexible lead through said bore.

29. A circuit interrupter comprising, in combination, a body of solid arc extinguishing material having a bore from the surface of which an arc extinguishing medium is evolved due to the heat of an arc, a pair of relatively movable apart terminals at one end of said bore between which an arc is adapted to be drawn in said bore, a flexible lead connected to one of said terminals and extending out of said bore, means for drawing said flexible lead through said bore on operation of the interrupter, and a pair of pins extending transversely across said here adjacent its other end and spaced apart such that said flexible lead is freely movable therebetween but the terminal attached thereto is not whereby the '=vement of said flexible lead is limited.

30. A circuit interrupter for use on high tension electric circuits comprising, in combination, a tubular insulating housing, a stationary terminal at each end of said housing, a body of solid are extinguishing material at each end of said housing, each having a longitudinal bore offset from the common central axis of each in opposite positions, a movable terminal within each bore between which and the adjacent stationary terminal an arc is adapted to be drawn, operating means for each movable terminal extending alongside the other operating means and adapted to withdraw the movable terminal individual thereto on the occurrence of a fault in the circuit, and means electrically interconnecting said movable terminals.

31. A circuit interrupter for use on high tension electric circuits comprising, in combination, a tubular insulating housing, a stationary terminal at each end of said housing, a body of solid arc extinguishing material at each end of said housing, each having a longitudinal bore offset from the common central axis of each in opposite positions, a movable terminal within each bore between which and the adjacent stationary terminal an arc is adapted to be drawn, a metallic fitting at the inner end of each bore through which the terminal individual thereto is movable, spring means biased between each metallic fitting and its movable terminal and lying alongside the other, spring means for withdrawing the movable terminals on the occurrence of a fault in the circuit, and means electrically interconnecting said movable terminals.

32. A circuit interrupter for use on high tension, electric circuits comprising in combination, a tubular insulating housing, a stationary terminal at each end of said housing, a body of solid arc extinguishing material at each end of said housing, each having a longitudinal bore offset from the common central axis of each in opposite positions, a movable terminal within each here between which and the adjacent stationary term a1 an arc is adapted to be drawn, a metallic fitting at the inner end of each bore through which the terminal individual thereto i movable, a metallic strut member in contact engagement with each said metallic fitting and extending alongside the other strut member into contact engagement with the other metallic fitting, and spring means interconnecting each movable terminal and the remote end of the strut member individual thereto for biasing the former for movement through its bore.

33. A circuit interrupter for use on high tension electric circuits comprising, in combination,

a tubular insulating housing, a stationary terminal at each end of said housing, a body of solid arc extinguishing material at each end of said housing, each having a longitudinal bore ofiset from the common central axis of each in opposite positions, a movable terminal within each bore between which and the adjacent stationary terminal an arc is adapted to be drawn, a metallic fitting at the inner end of each bore through which the terminal individual thereto is movable, a metallic tubular member secured to each said metallic fitting in alignment with its bore and extending alongside the other tubular member into contact engagement with the other metallic fitting, and a coil tension spring within each metallic tubular member and strained be-' tween the remote end thereof and the movable terminal individual thereto for drawing it through its bore to extinguish an arc therein.

34. A circuit interrupter for use on high tension electric circuits comprising, in combination, a tubular insulating housing; a generally cylindrical replaceable circuit interrupting device including blast action are extinguishing means at each end electrically interconnected, and a. fixed terminal at each end through which the arc extinguishing means thereat can discharge; an external terminal at each end of said tubular insulating housing through which said are extinguishing means can discharge and one of which is adapted to receive said replaceable circuit interrupting device, said fixed terminals registering with said external terminals when said replaceable circuit interrupting device is placed in operative position within said tubular insulating housing, and clamp means individual to each pair of registering terminals to provide electrical connection therebetween and to securely hold said replaceable circuit interrupting device against movement relative to said tubular insulating housing.

35. In combination, a pair of blast action circuit interrupting means positioned end-to-end and adapted to discharge in opposite directions, means positioned between said circuit interrupting means for operating the same, and metallic strut means electrically and mechanically interconnecting said circuit interrupting means.

36. In combination, a pair of blast action circuit interrupting means positioned end-to-end and adapted to discharge in opposite directions, a metallic tubular member electrically and mechanically interconnecting said circuit interrupting means, and means within said metallic tubular member for operating said circuit interrupting means at the ends thereof.

37. A circuit interrupter comprising, in combination, a tubular insulating housing, generally cylindrical replaceable circuit interrupting means adapted to be removably mounted within said housing, terminals at the ends of said replaceable circuit interrupting means one having a head portion and the other being generally cylindrical, ring-like terminals at the ends of said tubular insulating housing one of which is adapted .to receive said replaceable circuit interrupting means therethrough until said head portion abuts the same while the position of said cylindrical terminal with respect to the other ring-like terminal is variable, means for clamping said head portion to said one ring-like terminal, and means for clamping said cylindrical terminal to the other ring-like terminal in any likely relative position.

HUGH A. TRIPLETT. 

